Furnace roof and removable gauge pin for determining the condition thereof



Patented Nov. 15, 1949 FUENACE EF AND REM0VABLE GAUGE PIN F0B DETEEMINING TIIE CONDITION THEEE0F 0@tober 21, 1946, serial N0.

17, 194S. Divide(l a'nd this 20, 1948, serial N0. 22,164

This invention relates to furnace roofs and nlore particularly to a roof for an open-hearth fufnace and a revable gauge pin for deter- Znining When it requires replaceent This is a division of nly application serial N'0. 704,645, iiled october 21 1946 which haS matured into Patent 1`To. 2 470,98 dated 1'Ia'y 17, 199 for "E'urnace roof and accessories therefor."

The roofs of open-hearth furnaces such as used in nlaking steel are Subjected to extre!nely severe working conditions and Inust be reconstructed periodica1y. This necessitates shutting down the furnace with a' consequent loss of production I I0t spots in the roof are a con110n cause of fai ure Since they result in accelerated 10calized dete- 'rioration by erosion They are caused by im proper f1alne distribution which cannot always be avoided. 1`Ton-uniforn tenlperature conditions of the thickness of the bricks of Which the roof is conlp0sed at various critical 10cati0!1s fro!n tilTle to tiIne during the life of the roof While the furnace is in 0peration, and thus pern1it an accurate estinate ofthe renaining life of the roof.

Another object is to provide a roof construction permitting the taking of temperature eadings either spot" o continuous," at desired critical locations and elevations without cutting into ol' over the area 0f the roof cause destructive vari ations of c0npressive stress in the brick co!nposing the r00f arch, by reason of differentia1 expansion and contraction IIot spots in the roof, furthern10re cause tenlperature differencS in the bath since the latter is heated by radiation from the name and r00f, and this condition in1pairs the quality of the product It is impossible to detern1ine the remaining life of a' r00f or the existence or location of hot Spots by visual inSpecion of the 10vver Surface thereof Even if it were, the necessity of opening the charging doors for a' tinle long enough to pernlit the inspection would be undesirable because of the induction of excess air, `10ss of heat and the danger of creating further ten1perature differ ences between various p0ints ih the bath ol` over the surface of the roof. If it were possible t() detect hot spots in the roof, the danger of acceler ted deterioration ould be reduced by shifting the direction of the ame somewhat Heretofore, it has been aSsumed that a roof is good for so nny heats, say 200, and that after that number has been reached, Tebuilding is necessary. vvhile hot spots in the furnace roof genenally indicate localized erosion to a dangerous v thinness, it has frequently been discovered, after the brickwork has been torn down, that the roof ctually was in better condition than anticipated and would have rendered good service for an on the other hand, son1etines weaker additional nulnber of heats the brickwork of the roof is than vvould appear, even though n0'hot Spos occur, With the end result that the r00 caves in.

It is the principal object of Iny invention, therefore, to provide a furnace roof vvith Ileans vvhich will !ake possible a quick and easy deter!ination vveakening the roof structure, and without neces- Sitating the opening of the charging doors of the furnace.

still another object is t0 provide a construction which permits the ready checking of the velocity 0f the na!ne vvithin the furnace, With the result that the direction and range there0f Inay be accurately controned A further object is the attainment of the fore going results at a low installation nd maintenance cost In a preferred enbodinlent of the invention, provide apertures in the brick arch forning the furnace roof, above certain critical p0ints distributed over the area of the hearth. '0 this end I lay a special brick in the roof above such points having a tapered bore threthrough. place a tapered sleeve or liner i1'the bore of each Such brick and t a tapered renovable plug or pin in each Sleeve The brick, sleeve a'nd pin a're conposed of refractory nlatel`ial Sinilar to that of which the other roof bricks are nlade They deteriorate by erosion and the like, therefore, at about the sazne rate as the other bricks in the vicinity 'he progress of such erosion Inay thus be readily observed from time to time by taking out the pins and observing their reduction in length. 'he apertures also permit temperature measurements to be Inade and the velocity of c0nbusti0n gses to be obseTved conplete understanding of the invention nlay be obtained from the following detailed description and explanation when read in c01junction With the acconlpanying drawings illuStrati 1g the present preferred enbodinent. In the dawings 1'igure 1 is a partial horizontal Section through one end of an open-hearth furnace indicating by intersecting center lines the 10cation of apertures in the roof of the furnace for the purp0ses 01' the present invention;

F'igure 2 is a partial vertical longitudinal section taken on line III Of Figure 1;

Figure -3 is a transverse Section taken on line IIIIII Of Figure l;

Figuie 4 is an axial section through one of the special bricks showing the sleeve a nd pin therein; 

